Improved bridge



/Yffr FRONT `ELEIAYION END ELEVATION SIDE ELEVATIUN SIDE ELevAnoN.

NAPETERS. PHOTO-LITHDGRAPHEH. WASHINGTON. D. CV v dilute-d @States CHARLES H. PARKR. OF BOSTON, MASSACHUSETTS.

Letters Patent N 100,185, dated February 2v2, 187i).

IMPROVED BRIDGE.

The Schedule referred to in these Letters Patent and making part of the same.

To whom it may concern Be it known that I, CHARLES H. PARKER, civil engineer, ot' Boston, in the count-y ot' Suffolk, and State ot' Massachusetts', have invented certain new and useful Improvements in the Construction of Bridges; and I hereby declare the following to be a full, clear, and exact descriptionot' the same,- reference beinghad tothe accompanying drawing, in whicl1 i Figure 1 is a side elevation of a bridge embodying my. invention.

Figures 2, 3, 4, and 5 are views representing indetail the construction and arrangement ofthe compression member.

Figures 6, 7 and S are like views of the skew-back or thrust-block.

Figure 9 is a view on an enlarged scale of the upper port-ion of one of the end panels of the structure.

The improvements in the construction of bridges which 1 desire to secure by Letters latcnt are as tollows:

to the construction of the end lpanels or bays ot a truss.

ln order to make a truss with a curved top member and straight bottom member, und sloping ends that shall be capable ot' being altered in lengt-h within certain limits, without changing the gnierall proportions of the truss in vother respects, l have designed the end panels, or in the following manner:

The truss is composed of a curved top member, a straight bottom member, and vertical posts or compression members A, with the usual system of longitudinal diagonal rods or braces.

vWith the vertical post at each end of the truss I combine the fractional length of the top member and a sloping end, as seen in the drawing, the curved top member being made some fractional lengthof the endv panel or hay, as shown at G, tigs. 1 and 9, und the balance ofthe length of this panel or bay being composed of the sloping end N, which .is riveted or otherwise secured to the curved top member G and to its point of support at its other end in any suitable mauner. 'lhe advantages ot' this plan are, that in practice if l wish to lengthen or shorten a given length of span within certain' limits, I have only to shorten or lengthen the fractional top member of the end bays or panels, or increase or decrease the' slope ot' the ends, without in any way altering or disturbing the patterns or dimensions or proportions ot' the vertical posts, or of that part of the truss between the end panels; and I am thus enabledin practice to make all patterns, measurements, and plansanswerfor dil'- ferent lengths of spans within certain limits.

Fil-sti The iirst portion of my invention relates Secondly. The second part of' my invention relates to an improvement in the construction ot' awroughtiron compression member, capable also of acting with equal eiiciency as a. tension member. lThe body of the I-beam and projecting lips D D, which t on each side ofthe web ofthe I-beam.

To join the eye to and virtually make it a part-of the |-.beam, I employ a strap of wrought iron, E, which passes around the outside and is recessed int-o the casting B at I, extending down over the lips D D 1 to the web of the I-beam A, to which it is securely The strap recessed into the casting, in connection with the proiecting lips D l), prevents any moving of the casting ti'om position.

lhehole through the castings fora pin or-rivet forms the means of connection of this member with the top und bottom members of a truss.

To lorm a connection with the bottom chord of a truss and the diagonals ofthe the web, a further modification, shown in figs. 2, 3, and 4, is introduced int-o the lower eye. This consists in casting into the eye a slot, S, land cutting into the encircling strap E a similar siot, aud then placing in this slot the eyes of the diagonals, so that by the common holt all are held in place. By this construction Imake a member `which is elective in resisting both compression and tension, ard is also capable ot'resistiug efectually any lateral moiioli.- y

Thirdly. The third portion of my invention relates to an improved block or skew-back, which is used in the end panels or bays. 'The general form of t iis block is shown in figs. 6, 7, and 8. Along eachside and around the end H is a recess, K, to receive the bar L, which passes completelyy around the thrust-block, and terminates at the ends in eyes or any equivalent instrumentalities to fasten' to the chord-bars of the bridge. To t'orm the connection with the sloping end N of the arch or top member G, the block projects into 'said ends. The thrustof this top member is received by a shoulder, O, cast upon the block aud the upper edges of the encircling strap L.

To give additional lateral, stilness, and to more vthoroughly join to the block the top member or arch, -I introduce the plates P P recessed into the block, :1nd under the encircling strap L'and under the side plates y ofthe arch or top member, the whole being fastened together by bolts or rivets It R, or any equivalent,

passing through the encircling strap L, the plates P,l l

into the block, and through the side plates of the arch or top member G, the plate P, and into the block; and also with bolts X, or any equivalent fastening, lthrough the top plate ofthe arch or top member into the block, tlms binding the whole together securely. The :advantages of this are, that the thrusts und pulls of the respective top and bottom members of :t truss are resisted by the block, which receives from these two members onlystrains of compression through the medium ofthe encircling strap L; und the bolts, xivets, or any equivalent used to fasten said members to the block, are not called upon to resist the direct strains from the seid top and bottom members.

what I claim as new, and desire to secure by Letters Patent, is

1. A truss having its vertical posts or compression members fraction-tl lengths ofthe curved top member, amd sloping ends combined in the end panels or bays, substantially in the manner und for the purpose specified.

2. A compression member of a. truss, constructed in the nimmer and for the purposes specified.

`3. The cust-iron eye or Aend of the compression member ot' u. truss, constructed with lips to fit the 6. The plate P, used in the manner and for the purposes specified.

7. The combination ofthe top and bottom members ol' e truss with the thrust-block, its encircling bnr or strap, and the stiifening-plete P, under the arrangementshowu and described.

In testimony whereof, I havesigned my ,name to this specilication before two subscribing witnesses.

. CEAS. H. PARKER.

Witnesses:

TnoMAs G. BANKS, GADwA-LLADER Gonny. 

